In order to fasten a conventional power module to a power conversion apparatus housing or the like, the power module is fastened to the device with a fastener member such as a bolt from the same direction as a fixing direction. Therefore, there is a need to ensure a tool space above an upper surface of the power module. Under the circumstances, diverse components of the power module are mounted away from the above space so as not to interfere with a tool. For that reason, there is a limit to the effective utilization of a space where the power module components are mounted. An example of a real fastening manner is disclosed in JP-A-2007-282370.